This proposal requests funding to support a new, state-of-the-art, high performance 129Xe gas polarizer, primarily for pulmonary imaging, which will initially be used by ten investigators at the University of Pennsylvania, Temple University and Columbia University. The proposed system will address the need of a large group of NIH-funded investigators from the Radiology, Pulmonology, and Anesthesiology and Chemistry departments at these institutions. The University of Pennsylvania has a wide assortment of polarization technology and polarizers, which include 3He gas and 13C polarizers (see Table C.1 for details). The University also has one of the earliest models of the MITI 129Xe polarizer, which is more than fifteen years old. This polarizer, when operational, can produce a small amount of 129Xe with a polarization level of about eight to ten percent. The capability of the system is extremely limited in performing any preclinical or clinical studies, as it cannot produce a sufficient amount of highly polarized 129Xe gas. In contrast, the system we have proposed to obtain, the Xemed XeBox E-10 polarizer, is capable of producing 129Xe gas samples with 4-5 times the polarization in approximately one sixth of the time. The requested gas polarizer will form the basis of a unique research resource with the ability to develop and test novel imaging and diagnostic techniques, and will lead to the development of non-invasive imaging metrics for the quantitative assessment of lung function and structure. At present, all of the NIH-funded pulmonary imaging work at the University of Pennsylvania is carried out using polarized 3He MRI. However, in recent years, the long-term viability of 3He as a lung imaging agent has become questionable due to its decreasing availability and ever- increasing price. The combination of these two factors has made it difficult - if not impossible - to carry out large-scae clinical studies, something that is needed in this field in order to develop specific biomarkers fo early detection of specific pulmonary disorders. These trials can be best supported using the rapid production, high polarization, and low operational cost of the proposed instrument~ furthermore, the rationale for doing so is provided by the large atmospheric Xe supply and consequent viability of 129Xe imaging in the clinic. We aim to develop a regional resource to support this translational effort.